1. Field of the Invention
This invention relates to a panoramic imaging arrangement of the kind capable of capturing, focusing, correcting aberrations and otherwise manipulating colored light received from a part of or all of a 360xc2x0 surrounding panoramic scene.
2. Discussion of Related Art
Paroramic imaging arrangements have become popular in recent years for purposes of viewing 360xc2x0 surrounding panoramic scenes. Older generations of panoramic imaging arrangements generally consisted of revolving periscope-like constructions having relatively complex mechanisms for revolving them. More recently, stationary panoramic imaging arrangements have been developed. A stationary panoramic imaging arrangement generally has one or more lenses, each having a vertical axis of revolution, which are used to refract or reflect light received from a 360xc2x0 surrounding panoramic scene. The lenses alter the direction of the light, after which the light passes through a series of lenses which are located vertically one above the other and which further manipulate the light by, for example, focusing the light or altering the intensity of the light.
The task of receiving light in a sideways direction and altering the direction of the light so that the light then proceeds in a vertical direction is a difficult one. Altering the direction of light to such a degree, especially when coming from a 360xc2x0 surrounding scene, often leads to aberrations in the resulting light. These aberrations may include astigmatism of the light, defects in color of the light, a loss of image plane flatness, and other defects, some of which are subsequently discussed in more detail.
Relatively complex lenses and lens arrangements have been developed in order to overcome these aberrations and produce an acceptable image. These lens arrangements usually include a large number of lenses and oftentimes have lenses with surfaces that are aspherical (see for example U.S. Pat. No. 5,473,474 issued to Powell). Aspherical lenses are difficult to manufacture and therefore are less practical to manufacture than for example spherical lenses.
Because of the astigmatism induced by steep surfaces, well corrected prior art panoramic optical systems (those that have angles substantially above and below the horizon) have some lenses/mirrors that are considerably larger than the image size. Thus, these optical systems are large and have a maximum clear aperture (largest required lens/mirror diameter) of more than 10xc3x97 the image diameter.
In addition, lenses that include voids (air spaces) can be more difficult to manufacture than solid lenses because of the difficulty in aligning the parts of the lens system.
It would be advantageous to have a panoramic imaging arrangement that is solid, is color corrected, has a maximum clear aperture (largest required lens/mirror diameter) of less than 8xc3x97 the image diameter, and has an increased aperture (of the order of F4.6 as compared to F20).
According to one aspect of the invention there is provided a panoramic imaging arrangement comprising a first and second transparent component both rotationally symmetric about an axis of revolution. The first transparent component has an upper surface and a lower surface. The lower surface includes a reflective portion and a refractive portion both about the axis of revolution. The refractive portion extends radially from the axis of revolution to the start of the reflective portion. The second transparent component is attached to the first transparent component at a refractive interface that extends into the upper surface. The second transparent component includes a distal reflective surface.
Light from a portion of a surrounding panoramic scene is refracted by a portion of the upper surface, is reflected by the reflective portion of the lower surface through the refractive interface to the distal reflective surface. Once reflected from the distal reflective surface, the light again passes through the refractive interface and exits the first transparent component through the refractive portion of the lower surface.
Another aspect of the invention is a partial panoramic imaging arrangement that includes a first transparent component about an axis of revolution. The first transparent component has an upper surface and a lower surface. The lower surface includes a first reflective portion and a refractive portion both of these portions about the axis of revolution. The refractive portion is radially inward from said first reflective portion. Light from a greater than 90xc2x0 surrounding partial panoramic scene, is refracted by a portion of said upper surface. The partial panoramic imaging arrangement also includes a second transparent component attached to the first transparent component at a refractive interface. The refractive interface, also about the axis of revolution and extending into the upper surface. The second transparent component also includes a distal reflective surface.
The foregoing and many other aspects of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiments that are illustrated in the various drawing figures.